The present invention relates to a mass or ion mobility spectrometer and a method of performing mass or ion mobility spectrometry. Embodiments of the present invention relate to a mass spectrometer or method of performing mass spectrometry employing ion mobility separation (“IMS”).
In conventional targeted mass spectrometry or tandem mass spectrometry experiments such as selected ion recording (“SIR”) or multiple reaction monitoring (“MRM”) the presence of known target analytes are confirmed during the course of a chromatographic separation by monitoring characteristic mass to charge ratio values. IMS separation is often used to add an extra degree of selectivity to these experiments.
Ions may be separated according to their ion mobility by virtue of their different interactions with a buffer gas under the influence of an applied electric field. The nature of the interaction between the analyte ions and the gas determines the collision cross-section and hence the measured drift time of ions through an IMS device.
Ions undergo similar interactions with the buffer gas in differential ion mobility separation (“DMS”) or field-assisted ion mobility separation (“FAIMS”) devices. Ions also interact with the background gas in other gas-filled devices such as proton transfer reaction (“PTR”) devices.
It is desired to provide an improved spectrometer and improved methods of spectrometry.
In particular, it is desired to be able to optimize the conditions within such gas-filled devices for multiple targeted ions during the course of an experiment.